Is it possible to create bi-directional relationships between nodes with the same label?

Question

Person node:

firstName
lastName
address
email
phoneNumber

Company node:

Name
address
email
phoneNumber

Relationships:

Person -[SPOUSE]-> Person
Person -[SIBLING]-> Person
Person -[FAMILY]-> Person
Company -[EMPLOYEE]-> Person

Person entity:

public class Person {
    @Id
    @GeneratedValue
    Long personId;

    @Builder
    public Test(Long personId, String firstName, String lastName, String address, String email, String phoneNumber) {
        this.personId = id;
        this.firstName = firstName;
        this.lastName = lastName;
        this.addresss = address;
        this.email = email;
        this.phoneNumber = phoneNumber
    }

    @NotEmpty(message = "Please provide a first name")
    String firstName;

    @NotEmpty(message = "Please provide a last name")
    String lastName;

    String address;

    String email;

    String phoneNumber;

    @Relationship(type = "SPOUSE",direction=Relationship.OUTGOING)
    public Set<Person> spouse;

    @Relationship(type = "SIBLING",direction=Relationship.OUTGOING)
    public Set<Person> sibling;

    @Relationship(type = "FAMILY",direction=Relationship.OUTGOING)
    public Set<Person> family;
}

When I create a Person for Jane I also add a sibling relationship with John.

Running person.fetchById("29d31f6c-edfe-48a2-9ab2-3baed5d5ae69") retrieves the node Jane with the corresponding sibling node John.

{
   "address":"",
   "email":"",
   "phoneNumber":"",
   "personId":"29d31f6c-edfe-48a2-9ab2-3baed5d5ae69",
   "firstName":"Jane",
   "lastName":"Smith",
   "spouse":null,
   "sibling":[
      {
         "address":"",
         "email":"",
         "phoneNumber":"",
         "personId":"f825cedd-7328-4f9d-b0fd-a33726814f25",
         "firstName":"John",
         "lastName":"smith",
         "spouse":null,
         "sibling":[],
         "family":null
      }
   ],
   "family":null
}

However, the sibling relationship should be bi-directional. Running person.fetchById("f825cedd-7328-4f9d-b0fd-a33726814f25") only retrieves the node John.

{
   "address":"",
   "email":"",
   "phoneNumber":"",
   "personId":"f825cedd-7328-4f9d-b0fd-a33726814f25",
   "firstName":"John",
   "lastName":"Smith",
   "spouse":null,
   "sibling":null,
   "family":null,
   "closeFriend":null,
   "friend":null
}

Here is where the problem lies. I could add another sibling relationship between John and Jane. But, this effectively creates a infinite loop between the two. And the output from person.fetchById ends up being garbage.

Is there any way to limit the depth of nodes returned when fetching nodes?
I'm new to neo4j, so I suspect my design is wrong. What is the best way to model this kind of relationship?

InverseFalcon InverseFalcon · Accepted Answer · 2021-03-31T19:25:43

You're using SDN here?

From the Spring Data Neo4j docs:

If you don’t care about the direction then you can specify direction=Relationship.UNDIRECTED which will guarantee that the path between two node entities is navigable from either side.

Is it possible to create bi-directional relationships between nodes with the same label?

2 Answers